The present invention relates to a breath-actuated administration of a dose of dry powder from a dry powder inhaler to a user, and more specifically the present invention relates to an arrangement for triggering off the process of delivering the dose to the user also involving opening and closing of an air inlet of a dry powder inhaler when subject to an inhalation operation.
Today supply and distribution of medical powders take place in many different ways. Within health care more and more is focussed on the possibility to dose and distribute powder directly to the lungs of a user by means of an inhaler to obtain an efficient, fast, and user-friendly administration of the specific medical substance.
Inhalers have been developed from being very simple to the up-to-date relatively complicated devices. For the up-to-date inhalers some form of mechanical dosing is almost entirely used for preparing the dose to be inhaled. Most often the dosing of the amount to be inhaled takes place industrially in advance in a dose package containing 5-50 doses. The inhaler then is loaded with this dose package as the source of each dose. Other inhalers have a magazine from which the powder is dosed by some device for distribution to the inspiration air. In both cases the powder will generally be strongly agglomerated and therefore must be dispersed.
There is a demand for arrangements improving and simplifying administration of medical powder by means of an inhaler providing a possibility to control the start of the inhalation airflow.
The present invention discloses an arrangement for triggering off a process of administering a dose of dry powder, for instance a medical drug, by the breath of a person inhaling through a dry powder inhaler (DPI). The arrangement also controls the opening and closing of an air inlet in the inhaler. Particularly the arrangement according to the present invention is to be applied in a new continuous inhaler, i.e. an inhaler that controls the powder concentration and the time interval of the dose delivery to the user, thereby achieving a number of advantages in comparison to inhalers marketed today.
The present arrangement requires a certain well-defined minimum pressure differential between a surrounding atmosphere and the airways of the inhaling person to trigger off the process of delivering the dose and to open an inlet for outside air to enter into the interior of the DPI. The arrangement controlling the triggering mechanism and the opening and closing of the inlet of air into the DPI presents a flap connected to a biased catch mechanism. The flap closes the air inlet of the DPI to the atmosphere by the force exerted by a spring, which acts on the flap through a mechanism of levers. In order to open the flap a force bigger than the closing force of the spring and lever mechanism must be applied. The necessary force ensues from the pressure differential across the flap resulting when the user sucks through the mouthpiece of the DPI to a certain degree. The catch is through the mechanism of levers released by the flap when the flap opens, and triggers a sequence of events constituting the irreversible process of administering a dose to the user upon his or hers inhalation through the inhaler. The mechanism of levers connecting the flap, the spring and the catch uses rounded shapes where moving parts are in contact with each other to minimize contact areas and rubbing effects and to achieve near zero friction losses. The biased flap is further provided with a counterweight accomplishing the flap and the catch-mechanism to be statically and dynamically balanced, which almost completely eliminates the risk that external forces, e.g., force of inertia, gravitation or blows to the DPI accidentally will trigger the process of administering a dose if, for instance, the device should be dropped.